I. Field of Invention
The invention relates generally to dummy bars for use in the start up of teeming in the continuous casting of strip in a steel strip casting machine of the type wherein at least a first set of driven rollers, or rolls, is disposed in spaced relation downstream from the outlet end of the mold. More particularly, the invention relates to a one-piece dummy bar including a contoured upper end adapted for connection to the forward end of the strip being cast, a sealing portion, and a lower portion adapted to engage the first set of rollers, or rolls, for the support and withdrawal the forward end of the strip from the mold.
II. Summary of the Prior Art
The use of dummy bars in the start up of teeming in the continuous casting of steel strip in a steel strip casting machine of the type wherein at least a first set of driven rollers, or rolls, is disposed in spaced relation downstream from the outlet of the mold is well known in the art. In use, the upper end of the dummy bar is located within the lower area of the mold temporarily sealing its outlet. Once the desired casting level is present in the mold and a loadable connection between the forward end of the strip and the upper end of the dummy bar has been formed, the bar facilitates the withdrawal of the forward end of the strip from the mold, and supports the strip until it engages the first set of driven rollers, or rolls.
Commonly known dummy bars include a starting head, or plug, having a contoured upper end adapted to form a connection between the itself and the forward end of the strip being cast as the melt flowing into the lower area of the mold hardens. This starting head is detachably connected to a rigid, or flexible, strand which allows the head to be withdrawn from the mold, and provides the required support for the forward end of the strip until it engages the withdrawal means directly. In addition, separate sealing means are generally provided between the starting head and the walls of the mold (at the so called sealing plane thereof) to prevent leakage of the melt and sticking of the starting head in the mold.
Multi part dummy bars of the type just described are expensive. They require special equipment for the manipulation, storage and transportation of their various components. In addition, special equipment is required to detach the cast strip from these dummy bars. Further, these special equipments are costly to acquire and maintain, and are subject to breakdowns, which can cause down periods for the entire casting operation. Still further, the assembly of such multi part dummy bars, and their disposition within the lower area of the mold, is a time consuming, and therefore costly, process.
Accordingly, it is an object of the present invention to provide a dummy bar for use with a strip casting machine, particularly a machine designed for the casting of strip having a thickness of less than 60 mm, which can be made economically.
It is also an object of the present invention to provide a dummy bar for use with a strip casting machine which is simple to manipulate, and hence timesaving to the strip casting operation as a whole.
Further, it is an object of the present invention to provide a dummy bar for use with a strip casting machine which avoids the need for special equipment for its transport and intermediate storage, and/or for the separation of the cast strip therefrom.
Still further, it is an object of the present invention to provide a dummy bar for use with a strip casting machine wherein the need for separate sealing means between the dummy bar and the broad side walls of the mold is unnecessary.